diving in august brazil, fernando de noronha: experiences, tips? recommended?

Hi,
we are planning our august holiday now and are thinking of diving and
trekking in brazil. excellent diving is the nr. 1 criteria.
for what we could find on internet the best spot for diving in brazil
is fernando de noronha. but how good is this? especially experiences
are very welcome: what viz, kinds of fish, any chance for pelagics,
big stuff? (apart from the dolphins there?)

thanx in advance, looking forward on any usefull comments!
kars